ucert: update to latest git HEAD

ucert: update to latest git HEAD

00b921d80ac0 Do not print line number in debug messages
96c42c5ed320 Fix length checks in cert_load()
fe06b4b836b3 usign-exec: improve usign -F output handling
19f9e1917e1b usign-exec: return code fixes
077feb5b5824 usign-exec: close writing end of pipe early in parent process
7ec4bb764e1e usign-exec: remove redundant return statements
5a738e549d31 usign-exec: change usign_f_* fingerprint argument to char[17]
112488bbbccc usign-exec: do not close stdin and stderr before exec
38dcb1a6f121 usign-exec: fix exec error handling
a9be4fb17df2 usign-exec: simplify usign execv calls
854d93e2326a Introduce read_file() helper, improve error reporting
afc86f352bf7 Fix return code of write_file()
fdff10852326 stdout/stderr improvements
dddb2aa8124d ci: fix unit test failures by enabling full ucert build
5f206bcfe5c2 ci: enable unit testing

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>